Pneumatic knit fabric tensioning devices for use with circular knitting machines

ABSTRACT

A tensioning device for use with a circular knitting machine includes a perforate duct extending below the needle cylinder and an imperforate discharge conduit extending from the lower end of the perforate duct. A control valve enables suction to be applied selectively to the exterior of the perforate duct and to the discharge conduit. In operation suction is applied initially to the discharge conduit until the leading end of a stocking enters the discharge conduit. The suction is then applied to the perforate duct and the stocking is thereby made to cling to the internal surface. When the stocking is completed suction is once again applied to the discharge conduit by the control valve.

[ Tune 12, 11973 IIIIited Etates Patent Mazri 54] PNEUMATIC KNIT FABRIC TENSIONING 3,443,403 5/1969 66/149 s DEVICES FOR USE WITH CIRCULAR FOREIGN PATENTS OR APPLICATIONS KNITTING MACHINES 987 852 3/1965 Great Britain.....................

[75] Inventor: Aramis Mazzi, Florence, Italy Solis S.ll.L., Firenze, Italy July 14, 1969 Primary Examiner-Wm. Carter Reynolds Attorney-McGlew and Toren [73] Assignee:

[22] Filed:

[57] ABSTRACT A tensioning device for use with a circular knitting ma- 21 Appl. No.: 291,416

S2 1 9M M W 1 W6 .0R W 9 4 u l 6 m in n c WM Mme S in I C 1 o .M e 0 0] EMF ll] 2 8 555 control valve enables suction to be applied selectively to the exterior of the perforate duct and to the discharge conduit. In operation suction is applied initially References Cited UNITED STATES PATENTS to the discharge conduit until the leading end of a stocking enters the discharge conduit. The suction is 3,517,529 6/1970 Currier.......................... 66/149 5 X then applied to the perforate duct and the stocking is thereby made to cling to the internal surface. When the 6 Claims, 3 Drawing Figures m I IL H n ma eihs .1

H6 ew 1 SLC 223 666 999 111 III 5 7 1 3,108,462 l0/l963 Tenconi.........1

3,273,360 /1966 Mahler.........................

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WVE/vmR RRAMtsMHZZ! BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a stocking tensioning device for use with circular knitting machines.

2. Description of the Prior Art Previously proposed pneumatically-operated takedown devices for tensioningstockings produced by a circular knitting machine have an intake conduit which extends downwardly from the needle cylinder and then curves away to form a pneumatic conveying conduit. When the stocking fabric during its formation reaches the conveying conduit, it tends to be retarded and then to be twisted within the length of conduit extending between the tensioning and conveying conduit and the knitting formation zone, which rotates with the needle cylinder. This twisting, which is unimportant for conventional stockings, becomes particularly difficult to solve when conventional stockings are replaced by a stocking having a greater length, such as knitted tights.

SUMMARY OF THE INVENTION According to the present invention there is provided, in a pneumatic tensioning device or takedown system for use with a circular stocking knitting machine, a hosiery accumulator to prevent twisting of stockings being formed during the knitting operation and prior to their being cast off by the needles of the knitting machine cylinder. The accumulator includes a sheath coaxially aligned below the needle cylinder of the machine, and a vertically disposed receiving means within and coaxial with the sheath, the receiving means having a hollow interior and open upper and lower ends positioned coaxial with and extending from within to below the needle cylinder. The lower portion of the receiving means, adjacent this lower end, is perforate, and at least this perforate portion of the receiving means is rotatable to constitute a rotary duct which is at least partially perforate. This rotary duct collects and rotates the stocking being knit at substantially the rotational speed of the needle cylinder. The hosiery accumulator further includes a suction and discharge conduit communicating with the lower end of the rotary perforate duct, a suction connection to the interior of the sheath, means for applying suction to the suction and discharge conduit, means for applying suction to the suction connection, and means for selectively activating one of the suction applying means, whereby suction is applied during initial formation of a stocking to the suction and discharge conduit and after the leading end of the stocking has just entered the suction and discharge conduit, suction is cut off from the latter and applied to the connection to the interior of the sheath thereby applying suction to the wall of the perforate duct to retain the stocking on the interior surface of the rotary duct. r

BRIEF DESCRIPTION OF THE DRAWINGS An embodiment of a tensioningdevice, or hosiery accumulator, in accordance with the invention for use with a circular knitting machine, will now be described, by way of example' with reference to the accompanying diagrammatic drawings, in which:

FIG. 1 is a vertical section of the device according to the invention, combined with the needle cylinder of a circular knitting machine;

FIGS. 2 and 3 show diagrammatically the pneumatic circuit, or takedown system, unit with an air control valve in two different positions.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, the needle cylinder 1 of a circular knitting machine is shown in outline, which cylinder is assembled on a stationary structure with which a support 3 (chain lines), underlying the needle cylinder, is also combined. The support 3 is arranged to hold a sheath 5 forming a part of a fixed casing of the device. The sheath is cylindrical and a closure wall 7 is secured across its upper end, which surrounds a part of a duct 9, which is relatively narrow and which is combined with a funnel portion 9A leading from an upper, open portion aligned with the working zone of the needles of the cylinder 1. A gearbox 10 has a casing which is rigid with the lower end of the sheath 5. The gearbox casing is formed by two portions 10A and 10B and has therein a pinion 12, drivable through a motion coupling 12A, and a gear 14 meshing with the pinion 12, which gear 14 is coaxial with the sheath 5 and with the duct 9 and funnel portion 9A. The gear 14 has a large central aperture and is rigid with a duct 16, extending internally the sheath 5 and mounted together with the gear 14 on the parts 5, 7, 10 by means of bearings 18 and 20. Duct 16 constitutes a tubular receiving means whose lowerportion, at least adjacent its lower end, is perforate and includes a plurality of apertures distributed along the'lower portion of the length of the duct 16 between the bearings 18 and 20. The apertures may have an increased density in the lower portion of the duct 16, that is in the portion nearer the bearing 20. A connection 22 to the cavity defined by the sheath 5, is also provided adjacent the lower bearing 20.

The lower portion 108 of the gear box 10 has an integral funnel-shaped projecting fitting 24, which is aligned with the aperture in the gear 14 and also the apertured duct 16. The free end of the fitting 24 is connected to a fixed conduit 26 which curves away from the device and forms a pneumatic conveying conduit for the removal of the knitted stocking.

FIG. 2 shows diagrammatically a pneumatic circuit unit, or takedown system, combined with the conduit 26 and with the connection 22. The conduit 26 leads to a chamber 28 where the knit fabric is collected. The chamber 28 is formed in part by a lower door 30 for the discharge of the fabric, and an upper mesh screen 28A. Suction is applied through a conduit 32 to the screen 28A. A conduit 34 communicates with the connection 22. The two conduits 32 and 34 communicate with a chamber 36 which, in turn, communicates through a conduit 38 with a fan unit 40. A shutter 42 is mounted in the chamber 36 and includes a part extending across a diameter of the chamber and an arcuate section part. The shutter 42 can be controlled through an external lever 44, a tie rod 46 and a rocker arm 48, by a cam 50A of a conventional program drum 50. Another cam 503 controls a rocker arm 52 arranged to operate the door 30.

In the position illustrated in FIG. 2, the valve shutter 42 is in a position wherein suction is transmitted through the conduit 26, the chamber 28, the conduit 32, the chamber 36 and the conduit 38. FIG. 3 illustrates a different position of the valve shutter 42, wherein suction is transmitted through the conduit 34 (and thus the connection 22), the chamber 36 and the conduit 38. In an intermediate position of the shutter 42, it is possible to shut the conduit 38 to cut off suction both from the conduit 26 and the connection 22.

The operation of the device is as follows:

At the start of the stocking formation, the connection 22 is closed and an air intake (suction effect) is provided through the conduit 26. When the initial portion M of the fabric M has reached the fitting 24 and the conduit 26 (and before reaching the first curve in the conduit 26), the suction applied to the conduit 26 is transferred to the connection 22 by the control system of the machine. Under these conditions, suction is continuously applied to the duct 9 and thereby a pneumatically-produced tensioning of the fabric being produced is continuously developed. However, the suction is also developed through the apertures in the duct 16 and the divided air-streams which are produced through these apertures tend to cause the fabric M to adhere along the duct wall, thus preventing the feed of the fabric into the conduit 26. As a result a more or less wrinkled or otherwise irregular configuration of the fabric is formed internally of the rotary duct 16 which rotates at the speed of the needle cylinder 1.

When the knit fabric has left the needle cylinder 1 the suction is restored to the conduit 26 and the suction is cut off from the connection 22. Under these conditions, the knit fabric is entrained pneumatically and the entraining takes place positively from the end M of the fabric, because of the presence of the end M in the conduit 26. The initial intake position in the conduit is thus maintained until the end M positively enters into the conduit 26.

The presence of the perforated duct 16 allows piling up of a length of fabric, and avoids the twisting of the fabric, since the delivery of the initial end M of the fabric, in the fixed delivery conduit 26 is interrupted at a desired level by a programmed control means.

The stocking is then positively extracted and always with the initially formed end preceding the remainder thereof. The stockings are delivered successively to the chamber 30.

I claim:

1. In a pneumatic tensioning device for use with a circular stocking knitting machine,

a sheath coaxial with and lying below the needle cylinder of the machine,

a rotary perforate duct disposed within and coaxial with the sheath,

a suction and discharge conduit communicating with the lower end of the rotary perforate duct,

a suction connection to the interior of the sheath,

means for applying suction to the suction and discharge conduit,

means for applying suction to the said suction connection, and

means for selectively activating one of the suction applying means whereby suction is applied during initial formation of a stocking to the suction and discharge conduit and after the leading end of the stocking has just entered the suction and discharge conduit, suction is cut off from the latter and applied to the connection to the interior of the sheath thereby applying suction to the wall of the perforate duct to retain the stocking on the interior surface of the rotary duct.

2. A device according to claim 1, further comprising a funnel-shaped duct disposed between the working zone of the needle cylinder and the end of the rotary perforate duct remote from the discharge conduit.

3. A device according to claim 1, wherein the said suction connection to the interior of the sheath is disposed adjacent the discharge conduit.

4. A device according to claim 1, further comprising a gear box disposed adjacent the discharge conduit,

said gear box including a gear wheel fast for rotation with the rotary duct.

5. A device according to claim 1, wherein said activating means comprises a suction fan,

a rotary air valve, and

cam means for operating said rotary air valve.

6. In a circular knitting machine, a needle cylinder, vertically disposed receiving means with a hollow interior and open upper and lower ends positioned coaxial with and extending from within to below the said needle cylinder, a lower portion of said receiving means adjacent said lower end being perforate, at least the perforate lower portion of said means being rotatable, first means for applying suction to said hollow interior through the said lower end, second means for applying suction to said hollow interior through said perforations, and control means for selectively operating said second means to apply suction to an article being knit and taken up through said hollow interior such that when the end of said article is vertically positioned near the said lower end a portion of the article adheres to the surface of said hollow interior at the said lower portion and the said article end substantially maintains this vertical positioning as knitting of the article continues, said control means selectively operating said second means to terminate suction and said first means to apply suction to said article when cast off. 

1. In a pneumatic tensioning device for use with a circular stocking knitting machine, a sheath coaxial with and lying below the needle cylinder of the machine, a rotary perforate duct disposed within and coaxial with the sheath, a suction and discharge conduit communicating with the lower end of the rotary perforate duct, a suction connection to the interior of the sheath, means for applying suction to the suction and discharge conduit, means for applying suction to the said suction connection, and means for selectively activating one of the suction applying means whereby suction is applied during initial formation of a stocking to the suction and discharge conduit and after the leading end of the stocking has just entered the suction and discharge conduit, suction is cut off from the latter and applied to the connection to the interior of the sheath thereby applying suction to the wall of the perforate duct to retain the stocking on the interior surface of the rotary duct.
 2. A device according to claim 1, further comprising a funnel-shaped duct disposed between the working zone of the needle cylinder and the end of the rotary perforate duct remote from the discharge conduit.
 3. A device according to claim 1, wherein the said suction connection to the interior of the sheath is disposed adjacent the discharge conduit.
 4. A device according to claim 1, further comprising a gear box disposed adjacent the discharge conduit, said gear box including a gear wheel fast for rotation with the rotary duct.
 5. A device according to claim 1, wherein said activating means comprises a sucTion fan, a rotary air valve, and cam means for operating said rotary air valve.
 6. In a circular knitting machine, a needle cylinder, vertically disposed receiving means with a hollow interior and open upper and lower ends positioned coaxial with and extending from within to below the said needle cylinder, a lower portion of said receiving means adjacent said lower end being perforate, at least the perforate lower portion of said means being rotatable, first means for applying suction to said hollow interior through the said lower end, second means for applying suction to said hollow interior through said perforations, and control means for selectively operating said second means to apply suction to an article being knit and taken up through said hollow interior such that when the end of said article is vertically positioned near the said lower end a portion of the article adheres to the surface of said hollow interior at the said lower portion and the said article end substantially maintains this vertical positioning as knitting of the article continues, said control means selectively operating said second means to terminate suction and said first means to apply suction to said article when cast off. 